Field of the Invention
This invention relates generally to computer networking and, more particularly, to the design of a network device.
Description of the Related Art
Personal computers (PCs) have recently joined television sets, high fidelity stereo equipment, and compact disc players as part of the vast array of electronic devices widely used in both the office and the home. The electronics marketplace has also seen a proliferation of appliances and personal electronics devices (consumer electronics devices) that use solid-state memory, in addition to devices that employ other widely used storage mediums. Some of the more popular consumer electronics devices include video cameras, photo cameras, personal digital assistants, portable music devices, as well as set top boxes, high definition (HD) television systems and digital recorders among others. The proliferation of such devices has correspondingly brought with it an emphasis on connectivity and networking for transferring data between the personal electronic devices, personal computers, and/or set top boxes.
In addition to specifications for internal busses, such as the Peripheral Component Interconnect (PCI), various interface standards for connecting computers and external peripherals have also been introduced, each aiming to provide simple connectivity at high speeds. Examples of such standards include the IEEE 1394 standard also referred to as FireWire, and the Universal Serial Bus (USB), both high-speed serial bus protocols. The most widely used networking standard for connecting computers in both Local Area Networks (LANs) and Wide Area Networks (WANs) has been the Ethernet protocol. More specifically, Ethernet is the IEEE 802.3 series standard, originally based on the Carrier Sense Multiple Access with Collision Detection (CSMA/CD) method that provided a means for two or more computer stations to share a common cabling system. CSM/CD has formed the basis for Ethernet systems that reached transfer speeds in the megabit range, that is the Mbit/sec range. Recent switched based and/or router based Ethernet systems are capable of supporting transfer rates in the Gbit/sec range. Ethernet generally makes efficient use of shared resources, is typically easy to reconfigure and maintain, and provides compatibility across many manufacturers and systems, while keeping the cost low.
However, Audio % Video (A/V) consumer entertainment systems such as HD televisions, set-top box and personal video recorders (PVRs) are generally not optimized for distributing/receiving high quality high resolution programming content through a standards based network, such as IEEE 802.3 Ethernet standard, IETF (Internet Engineering Task Force), and/or RFC (Request For Comments) compliant protocols. This typically holds for broadband Ethernet connections as well. One issue that has presented a problem in the development of entertainment systems has been the migration from closed networks—which may include proprietary, special purpose Ethernet Switch fabrics—to an open network, while maintaining performance levels required in the distribution of higher quality/resolution A/V programming content. It has also become increasingly difficult, if at all possible, to obtain the desired performance levels while moving real-time streaming data over a limited bandwidth local bus, utilizing standard Ethernet controllers. In addition, the generally high prices of consumer electronic products featuring Ethernet network components have made it difficult to assemble systems at reasonable costs.
Certain complexities inherent in the transmission of real-time and non-real-time audio/video data do not present a problem when employing data transport models and/or approaches such as digital satellite, cable, and terrestrial and proprietary, special purpose transmission systems. Digital satellite, cable and other proprietary, special purpose transmission systems are typically considered to be “closed networks”. Generally, a “closed network” in this context refers to a solution based on specifications not available to the general public. A proprietary solution will typically afford an individual manufacturer or group of manufacturers the time and resources to develop unique solutions that may achieve the desired performance goals, but such solutions will not usually interoperate with competing products. Examples of proprietary, special purpose solutions typically include digital video broadcasting through Cable TV (CATV) Networks, digital video broadcasting over Public Switched Telephone Networks (PSTN) and/or Integrated Services Digital Networks (ISDN), and digital video broadcasting through Satellite Master Antenna TV (SMATV) distribution system networks. A variety of special purpose network standards have been defined for various physical and transport models, and implemented under standards bodies, such as the DVB-ETSI (European Telecommunications Standards Institute), for example. The overall content distribution system is typically controlled by broadband network providers such as Cable Vision, Comcast and Direct TV. A broadband network provider typically dictates the hardware, software and protocols used in such a system.
In contrast, in an “open” network the hardware, software and the corresponding protocols are all defined by well-known standards with solutions readily available from different manufacturers, where such solutions are generally interoperable with each other. Additionally, an open network is a shared network, with potentially numerous service and content providers using the shared network to distribute content. As previously mentioned, one example of an open network is the IETF, which is a large, open community of network designers, operators, vendors, and researchers whose purpose is to coordinate the operation, management and evolution of the Internet, and to resolve short-range and mid-range protocol and architectural issues. Open network protocols are layered, based on the International Standards Organization (ISO) networking model. Any given open network generally has additional overhead depending on the network protocols used while communicating through the open network. Many, if not all current solutions do not have the system resources to support an open network model while processing higher quality and resolution A/V programming content. In addition, resource provisioning is typically more difficult to manage on such open networks.
Because broadband A/V distribution has historically been performed by satellite and cable services utilizing set-top-box (STB) and personal video recording (PVR) devices, the dissemination of A/V content using Ethernet as the primary method of distribution produces additional challenges. Existing A/V solutions generally use Ethernet connectivity at typical data rates of 1 to 6 Mbits per second for activities such as Internet web surfing, and as a return path for video-on-demand (VOD) applications, billing systems, and limited A/V distribution in the home. Bandwidth requirements for streaming higher quality video and/or audio content are substantially higher. For example, to support one High Definition (HD) video stream, a throughput of 12 to 60 Mbits per second with possibly some form of priority bandwidth provisioning, including QOS (Quality of Service), may be required. The need for QOS is usually determined by buffering and latency. For example, increased bandwidth requirements may necessitate an increased QOS in case a time delay between switching video content channels exceeds the average acceptable time elapsed between channel selections made by a user while “channel surfing”, due to buffering delays. Distribution of A/V data must preferably remain steady with minimal delays. With existing Ethernet solutions, achieving the required performance levels is typically very difficult if at all possible.
In addition, STBs and other consumer electronics devices are generally very cost sensitive. Most embedded processors and hardware building blocks comprised in the bulk of consumer electronics devices are usually low cost and feature limited performance (typically referenced as millions of instructions per second (MIPS)). Trade-offs between memory access speeds, CPU speed, and power consumption are quite common. For most system designers, migrating to an open network with its additional network processing overhead, when the CPU bandwidth is just enough for the core application, might necessitate migrating to a more expensive system solution. In addition, with this additional network overhead, utilizing a standard Ethernet controller will typically not give the performance needed to enable an open network solution, especially when aiming for low cost consumer electronics products.
The concept of transferring real-time and non real-time video and audio content over a shared and open network has been addressed in a variety of ways. For example, wireless modulation solutions such as 801.11a, b and g have been considered for shared access local area networks. Wired solutions such as 802.3 10/100/1000 Base-T twisted wire pair encoding solutions have also been considered. Numerous solutions have also been described at the media access and transport level. Some of these solutions include methods of media access using Ethernet 802.3, Wireless, 802.11a,b and g and other solutions such as Asynchronous Transfer Mode (ATM), Synchronous Optical Networking (SONET), and others. Additionally, various methods to achieve a higher QOS have been addressed by certain proprietary solutions.
One approach involves the concept of “transmission profiles”, where network systems and aggregators select paths by detecting additional information in the network packet, as in an Ethernet packet. In other cases Virtual Local Area Network (VLAN) tags are utilized, or ATM is implemented utilizing (virtual) path identifiers. Some solutions implement data bandwidth allocation, where network systems may be architected such that high-speed access is provided over frequency-division multiplexed (FDM) channels, enabling transmission of Ethernet frames and/or other data across a cable transmission network or other form of FDM transport. Devices would typically allocate downstream and upstream bandwidth on previously defined frequency channels based on time slot assignments for various network packets. In terms of transport, many current solutions utilize the Internet Protocol (IP). In some cases, various connection-oriented protocols such as Transmission Control Protocol (TCP) are employed.
However, most existing systems typically do not offer an open network solution built around standard and widely used network protocols (e.g. the Ethernet protocol) that is capable of maintaining performance levels required in the distribution of higher quality and resolution A/V programming content. For example, current systems utilizing standard Ethernet controllers generally do not allow for movement of real time streaming data over a limited bandwidth local bus, thus failing to achieve desired performance levels.
Other corresponding issues related to the prior art will become apparent to one skilled in the art after comparing such prior art with the present invention as described herein.